1. Field of the Invention
The present invention is directed to a sensor for inertial and/or rotational movements of an object or a life form, in particular to a sensor for movements of a human subject.
2. Description of the Prior Art
It is desireable to control the pacing rate of heart pacemakers in dependence upon selected physiological parameters which are a measure of the physical activity of the patient. A pacemaker of this type is known, for example, in U.S. Pat. No. 4,428,378, wherein a microphone is used as a sensor.
In such conventional devices, however, a number of unwanted signals are acquired simultaneously with the signals corresponding to the activity of interest, such unwanted signals, for example, resulting from respiratory and cardiac noises or noises deriving from sources outside of the patient. The disturbances picked-up by conventional sensors are also dependent on the physical characteristics of the patient, i.e., on the corpulence or muscularity of the patient, so that relatively complex sensitivity adjustments differing from patient to patient with different noise suppression characteristics must be undertaken.